Automatically self-regulating variable-stroke, variable-rate and quiet-operating pile driver apparatus

ABSTRACT

Automatically self-regulating variable-stroke, variable-rate and quiet-operating pile driver apparatus are disclosed in which a massive piston weight is bounced upon a cushion of pressure fluid, the pile driver advantageously being adapted for operation in four different modes: (1) only double-acting, (2) singleacting automatically converting to double-acting at maximum stroke travel, (3) only single-acting, (4) pre-stressing plus impacting plus thrusting mode, and (5) pile extraction mode. The prolonged downward push resulting from the pressurized fluidcushioned bouncing action is more effective than the conventional sharp hammer-type blow resulting from impact of one solid mass against another. When the pile being driven encounters softer strata in the earth, in the single-acting mode, the stroke of the piston weight automatically shortens while the number of bounces per minute automatically increase thus increasing the rate of the quiet powerful bounce thrusts for driving the pile faster, and when harder strata are encountered, the piston weight automatically bounces higher providing a longer stroke with fewer bounces per minute, thus increasing the force of each quiet powerful thrust for overcoming the increased impedance being encountered. In the double-acting mode, when harder strata are encountered, the velocity and stroke length of the piston weight increase automatically to deliver more powerful thrusts. A relatively large number of driving thrusts per minute can be provided in the double-acting mode by changing the head plug mass to shorten the maximum stroke length to increase the frequency of thrusts per minute. By virtue of the pressure fluid bouncing action imparted to the massive piston weight, the noise of metalto-metal contact blows can be avoided, and in addition a muffler housing surrounding the ports through which the expanded pressure fluid is released muffles the sound of the flow of the fluid, such as air or steam; this muffler also serving to separate lubricating oil from the released fluid. A cylinder bottom assembly below the bounce chamber is coupled to the pile being driven to transmit the quiet powerful bounce thrusts to the pile, moving in accordance with the pile motion, and a driving fluid storage chamber and valve mechanism associated with this assembly control the flow of the pressure fluid in an automatically selfregulating manner to seek the most effective driving action from moment-to-moment as the pile encounters different strata. If desired, the bouncing action of the cushion of pressure fluid can be altered to permit the piston weight to strike bottom slightly to provide the driving mode (4) above. A self-contained lubrication system may be actuated by the pressure impulses in the bounce chamber.

United States Patent 1 Chelminski AUTOMATICALLY SELF-REGULATINGVARIABLE-STROKE, VARIABLE-RATE AND QUIET-OPERATING PILE DRIVER APPARATUS[75] Inventor: Stephen V. Chelminski, West Redding, Conn.

[73] Assignee: Bolt Associates, Inc., Norwalk,

Conn.

[22] Filed: Aug. 14, 1972 [21] Appl. N0.: 280,547

Related US. Application Data [62] Division of Ser. No. 102,325, Dec. 29,1970, Pat. No.

12/1968 Duyster etal. 61/535 X Primary ExaminerErnest R. PurserAttorney, Agent, or FirmRoland T. Bryan et a1.

[ 5 7 ABSTRACT Automatically self-regulating variable-stroke,variablerate and quiet-operating pile driver apparatus are disclosed inwhich a massive piston weight is bounced upon a cushion of pressurefluid, the pile driver advantageously being adapted for operation infour different modes: (i) only double-acting, (2) single-actingautomatically converting to double-acting at maximum stroke travel, (3)only single-acting, (4) pre-stressing plus impacting plus thrustingmode, and (5) pile extraction mode. The prolonged downward pushresulting from the pressurized fluid-cushioned [111 3,788,402 Jan. 29,1974 bouncing action is more effective than the conventional sharphammer-type blow resulting from impact of one solid mass againstanother. When the pile being driven encounters softer strata in theearth, in the single-acting mode, the stroke of the piston weightautomatically shortens while the number of bounces per minuteautomatically increase thus increasing the rate of the quiet powerfulbounce thrusts for driving the pile faster, and when harder strata areencountered, the piston weight automatically bounces higher providing alonger stroke with fewer bounces per minute, thus increasing the forceof each quiet powerful thrust for overcoming the increased impedancebeing encountered. In the double-acting mode, when harder strata areencountered, the velocity and stroke length of the piston weightincrease automatically to deliver more powerful thrusts. A relativelylarge number of driving thrusts per minute can be provided in thedouble-acting mode by changing the head plug mass to shorten the maximumstroke length to increase the frequency of thrusts per minute. By virtueof the prescylinder bottom assembly below the bounce chamber is coupledto the pile being driven to transmit the quiet powerful bounce thruststo the pile, moving in accordance with the pile motion, and a drivingfluid storage chamber and valve mechanism associated with this assemblycontrol the flow of the pressure fluid in an automaticallyself-regulating manner to seek the most effective driving action frommoment-to-rnoment as the pile encounters different strata. If desired,the bouncing action of the cushion of pressure fluid can be altered topermit the piston weight to strike bottom slightly to provide thedriving mode (4) above. A selfcontained lubrication system may beactuated by the pressure impulses in the bounce chamber.

19 Claims, 21 Drawing Figures This is a division of application Ser. No.102,325, filed Dec. 29, 1970, and now US. Pat. No. 3,714,789.

BACKGROUND INFORMATION Conventional pile drivers of the diesel type usea falling piston or those of the steam type use a falling ram of greatweight to strike down upon an anvil surface to transmit the blow to thepile. Such conventional pile drivers have a disadvantage in the factthat they transmit the energy of the falling mass by a striking-typeblow on an anvil surface. Each blow produces a very loud noisy sound ofmetal-to-metal contact which is annoying to many persons, includingpersons who are located at a relatively great distance from theconstruction site. This noisy blow, especially in the conventionalsteam-type open striking hammer, is, in my opinion, a relativelyunsatisfactory method of transmitting energy to the pile for the purposeof driving the pile, because of the suddenness and short duration ofthis type of blow. Also, the forces on the anvil and on the pile becomedestructive when the energy levels needed to drive a pile become high.

Because of the metal-to-metal contact, the impact tends to bedestructive to the pile driver itself and to the pile being driven.There are many instances when shock-absorbing materials must beinterposed between the striking parts and the pile. The shock-absorbingmaterials which are conventionally used are wooden blocks, or pads, ofphenolic laminates, or other plastic materials. The use of such shockabsorbers wastes energy, and since they areexpendable and need to bereplaced, there is a resulting added cost for the pile drivingoperation.

It can be said that the prior art pile drivers are ofte noisy.

Another disadvantage inherent in the conventional steam-type pile driverlies in the longer period of time it takes for this type of driver toraise its hammer weight up from the anvil to the top of its travelbefore releasing the steam to expand to atmospheric pressure. The release of the steam drops the hammer weight to fall upon the anvil.

As further background information, it is noted that there is anadvantage in providing a relatively large number of driving thrusts perminute to a pile being driven. The reason for this advantage is that thesoil adjacent to the pile remains in a more or less agitated state whenfrequent driving thrusts are applied to the pile. Consequently, thefrictional force is reduced and the pile is relatively easier to drive.Conversely, when the driving thrusts are less frequent, the soiladjacent to the pile has an opportunity to slump down to becomemorefirmly seated against the side surfaces of the pile, which increasesthe frictional force so as to make the pile much more difficult todrive.

DESCRIPTION Accordingly, it is among the objects of the presentinvention to avoid undue noise, to overcome other disadvantages of theprior art, and to provide more effective and efficient pile-drivingoperations.

Other objects of the present invention are to provide a noveladvantageous and effective automatically selfregulating variable-stroke,variable-rate and quietoperating pile driver method and system wherein amassive piston weight is bounced upon a cushion of pressure fluid.

It is an advantage of a pile driver embodying the present invention thata prolonged downward push or thrust results from the pressurizedfluid-cushioned bouncing action of the massive piston weight assembly.This prolonged downward push or thrust is more effective and moreefficient than the conventional sharp hammer-type blow resulting fromimpact of a solid mass against an anvil. This prolonged downward push orthrust is less damaging to the pile driver and to the pile than thesharp hammer-type blow of a solid mass against an anvil which is typicalof many prior art pile drivers.

Among the advantages of the present invention in certain of its aspectsis that the pile driver embodying these aspects of the invention isadapted for operation in five different modes: (l) solely double-acting,(2) single-acting automatically converting to double-acting at themaximum stroke travel, (3) only single-acting, (4) pre-stressing plusimpacting plus thrusting mode, and (5) in a pile extraction mode.

Among the advantages provided by the pile driver methods and systemsembodying the present invention are those resulting from the fact thatin the singleacting mode when the pile being driven encounters softerstrata in the earth, the stroke of the piston weight automaticallyshortens while the number of bounces per minute automatically increase,thus increasing the rateof the quiet powerful bounce thrusts for drivingthe pile faster. When harder strata are encountered, the piston weightautomatically bounces higher providing a longer stroke with fewerbounces per minute, thus increasing the force of each quiet powerfulthrust for overcoming the increased impedance being encountered.

[n the double-acting mode, when harder strata are encountered, thevelocity and stroke length of the piston weight automatically increaseto deliver more powerful driving thrusts. A relatively large number ofdriving thrusts per minute can be provided in the doubleacting modebychanging the head plug mass to shorten the maximum stroke length toincrease the frequency of thrusts per minute.

Another advantage is that a pile driver, according to the presentinvention, can be equipped with a muffler housing surrounding the portsthrough which the expanded pressure fluid is released to muffle thesound of the escaping pressure fluid, such as air or stream. The

muffler also can be used to separate lubricating oil from the releasedfluid.

Among the further advantages provided by the present invention is thatthe quiet, powerful driving thrust applied to the top of the pileendures for a longer period of time during each driving bounce, anddestructive forces on the pile are substantially reduced as comparedto aprior art impact-type pile driver providing a comparable driving rate.

In accordance with one aspect of the present invention, there isprovided a controlled release of pressure fluid into the bounce chamberbeneath the massive piston weight to transfer the kinetic energy of thefalling piston weight to the pile at a controlled rate to lower theamount of destructive forces being applied to the pile while lengtheningthe useful driving push being ap- 3 plied to the pile. The pressurizeddriving fluid is released into the bounce chamber from a driving energychamber. This driving energy chamber is positioned closely adjacent thebounce chamber, and it is adapted to communicate directly with thebounce chamber when a release valve is actuated by the piston weight.Moreover, the piston weight is reaccelerated upwardly, in a bounce by acushion of the pressure fluid, thereby providing further extension intime of the useful driving thrust, thereby driving piles in an effectiveand. efficient method.

In accordance with the present invention, there is a self-regulatingdistribution of the driving energy between the bouncing massive pistonweight andthe cylinder bottom assembly which is coupled to the pile.When the pile is being driven through relatively soft material,affording low impedance to the penetration of the pile, the injectedpressurized fluid in the bounce chamber is able to push the cylinderbottom assembly downwardly a greater distance. Thus, during the bounce,there is an increased relative expansion of the pressurized fluiddownwardly and a corresponding decreased relative amount of expansionthereof upwardly as the pressure fluid in the bounce chamberreaccelerates the massive piston weight upwardly. There is a lessresultant upward velocity of the piston weight, and its stroke (ortravel) is correspondingly relatively short. In the single-acting mode,this short stroke provides a relatively rapid cycle time as compared toa longer stroke.

When harder strata are encountered by the pile, affording a greaterimpedance to its penetration, the pressurized fluid in the bouncechamber pushes the cylinder bottom assembly downwardly a shorterdistance. Thus, during the bounce, there is a decreased relativeexpansion of the pressurized fluid downwardly. A corresponding increasedrelative amount of upward expansion of the fluid occurs as itre-accelerates the piston weight upwardly. The result is that there isincreased upward velocity of the piston weight. Accordingly, its strokeis increased so that it goes higher in the upper cylinder. It therebyaccumulates more potential energy to be applied to driving the pileduring the next bounce to provide a more powerful thrust. This increasein driving thrust occurs for both the singleacting or double-actingmodes. The foregoing two paragraphs explain my theory of theself-regulating distribution of the driving energy between the bouncingmassive piston weight and the cylinder bottom assembly, as occasioned bythe impedance being encountered by the pile.

In addition, it is noted that the energy provided by the injectedpressurized fluid is effectively utilized because the portion of thisenergy which was not used to drive the pile is employed to re-acceleratethe piston weight upwardly at an increased velocity.- Thus, this portionof the energy is substantially conserved (minus friction and heatlosses) by being converted into increased potential energy to beutilized to provide a more powerful thrust on the next bounce.

The deceleration and re-acceleration of the massive piston weighteffectively utilizes not only the force applied in decelerating thepiston weight at the end of its downward stroke, but also effectivelyutilizes the reaction to the re-accelerating force applied to the pistonweight during the period of time such force is being applied to thepiston mass to re-accelerate it up again toward the top of its stroke.Thus, an enduring downward thrust or push is created during the entiredeceleration and re-acceleration.

If desired, the bouncing action of the cushion of pressure fluid in thebounce chamber can be altered to permit the piston weight to strikebottom slightly. The resulting driving mode on the pile is to pre-stressthe pile, then impact, then thrust it down. The pre-stressing occurswhile the cushion of pressure fluid is decelerating the piston. Thispre-stressing removes all of the play between the cylinder bottomassembly and the pile. Then, when the piston weight strikes bottom withan impact, the resulting blow starts the pile moving downwardly. Thesubsequent re-acceleration of the piston weight upwardly by the pressurefluid provides an enduring thrust which continues to push the movingpile down further.

In the presently preferred embodiment, the cylinder bottom assemblyincludes a second piston located below the bounce chamber in which thepressure fluid operates. This second piston is coupled to the pile beingdriven to transmit the quiet powerful bounce thrusts to the pile, movingin accordance with the pile motion. A driving energy pressurized fluidchamber is associated with this second piston and a valve mecha nisminjects a quantity of the pressure fluid automati cally from the drivingenergy chamber into the bounce chamber. A self-regulating driving actionoccurs as explained above to seek the most effective driving action frommoment-to-moment as the pile encounters different strata.

An advantageous self-contained lubrication system is actuated by thepressure impulses in the bounce chamher.

A muffler housing surrounds the ports through which the expandedpressure fluid is discharged into the atmosphere to muffle the sound ofthe flow of fluid. This muffler also serves to separate the lubricatingoil from the discharged fluid so as to recaptrue the lubricating oil.This recaptured oil is returned to the self-contained lubricating systemfor re-use therein,

Additional advantages flowing from this invention are simplicity andreliability of design and construction of the pile drivers with very fewmoving parts.

The pressure fluid utilized can be compressed air or steam or any othersuitable pressurized gas or vapor. As i used herein, the termpressurized fluid or pressure fluid isintended to include compressedair, steam or other suitable pressurized gas or vapor. In theillustrative embodiments shown, it is my preference to utilizecompressed air as the pressurized fluid" to operate the pile driver.

The various features, aspects and advantages of the automaticallyself-regulating variable-stroke, variablerate and quiet operating piledriver method and system of the present invention will become more fullyappreciated from a consideration of the following detailed descriptionin conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a pressure fluid actuated piledriver system embodying the present invention, shown on greatly-reducedscale from actual size;

FIG. 2 is a cross-sectional view taken along the line 22 in FIG. 1 asseen looking downward, being shown on a slightly larger scale than FIG.1;

FIG. 3 is a vertical axial sectional view, shown somewhat furtherenlarged, with the massive piston weight the muffler housing taken alongthe line 6-6 in FIG. 5.

FIG. 7 is an elevational sectional view of the portion of the piledriver system containing the oil filter and the self-actuatedlubrication pump for supplying lubricating oil to the moving parts ofthe pile driver. FIG. 7 is drawn on a scale of approximately one-halfactual size;

FIG. 8 is an elevational sectional view of the inlet arrangement for thepressurized fluid, with the connection for injecting the lubricating oilinto the pressure fluid being shown;

FIGS. 9, 10, 11, 12, 13 and 14 are vertical axial sectional viewssimilar to FIG. 3, but shown on somewhat smaller scale than in FIG. 3.These FIGS. 9, 10, 11, 12, 13 and 14 show the successive operatingpositions of the few moving parts of the pile driver system occurringduring one cycle of operation for delivering a powerful push or thrustto the pile being driven. It is noted that the operating positions shownin FIG. 3 are intermediate those shown in FIGS. 9 and 10;

FIG. 14 shows the massive piston weight being operated in thedouble-acting mode;

FIG. 15 is a vertical axial sectional view of the upper portion of thepile driver, with the operation being in the single-acting mode;

FIG. 16 is similar to FIG. 15, except that the operating mode issingle-acting converting to double-acting at maximum stroke travel asshown;

FIG. 17 is a side elevational view of the pile driver operating in theextraction mode with a pressure fluid cylinder and piston included inthe suspension line for limiting the maximum load applied to thesuspension equipment, such as a crane, and for isolating the suspensionfrom the jarring effects of the pile driver acting in the extractionmode;

FIG. 18 is a side elevational view and partial sectional view as seenalong the line 18-18 in FIG. 17;

FIG. 19 is an elevational sectional view of the pile driver adapter andconical guide used for driving wooden piles;

FIG. 20 is a vertical axial sectional view showing a modified embodimentof the invention; and

FIG. 21 is a vertical axial sectional view of another embodiment.

With reference to FIGS. 1-4, an automatically selfregulatingvariable-stroke, variable-rate and quiet op erating pile driver methodand system 20 are shown embodying the present invention. The pile driversystem-20 comprises a cylinder wall 22 surrounding a cylinder 23provided with a massive piston weight assembly, generally indicated at24 (See FIG. 3). At the lower end of the cylinder wall 22 is a'cylinderbottom assembly, generally indicated at 26, effectively closing offthelower end of thecylinder wall 22. The cylinder bottom assembly 26 iscoupled to the pile 28 being driven by a detachable coupling 30 and apile-driving adapter 32 which is shaped so as to engage the upper end ofthe particular pile being driven.

When it is desired to drive a pile having a different size or adifferent configuration (such as pipe pile, H- beam pile, timber pile)then the coupling 30 is temporarily disconnected, and a differentadapter 32 is inserted for providing the desired engagement with thepile. A pipe pile 28 is shown in FIGS. 1 and 3, but this is illustrativeonly. It is to be understood that the present invention can be used toadvantage for driving any type of drivable pile.

There is a bounce chamber 34 (FIG. 3) which is lo cated within thecylinder wall 22 between the lower end of the massive piston weightassembly 24 and the cylinder bottom assembly 26. Pressure fluidinjection means 36 are provided for suddenly injecting pressurized fluidinto the bounce chamber 34 beneath the descending piston weight assembly24. This fluid injection means 36 includes a pressurized driving fluidstorage chamber 38 and a control valve mechanism 40 which communicateswith the bounce chamber 34.

The massive piston weight assembly 24 moves up and down within thecylinder 23, and it bounces upon a cushion of pressurized fluid in thebounce chamber 34. The manner in which the pressurized fluid is injectedinto the bounce chamber, and the many advantages which accrue from theadvantageous massive piston bouncing action are indicated in theintroduction and will be described further below.

The massive piston weight assembly 24 includes a main weight 42 ofsuitable massive and strong material. For example, in this illustrativeembodiment, the main weight 42 is a solid steel member of generallycylindrical configuration with bearings, piston rings and end capsattached to its lower and upper ends. Its lower and upper ends areidentical in construction, and so only the lower end is shown in detailin FIG. 3 in order to simplify and clarify the drawings. If it isdesired to see the upper end of the piston weight assembly 24, it isnoted that this can be seen in FIGS. 2, 14, 15, and 16.

Referring particularly to FIGS. 3 and 7, it is seen that a bearingsleeve member 44 is mounted on each end of the main weight 42. Thissleeve member 44 has an annular configuration and fits onto a reduceddiameter end portion 46 at the end of the weight 42, abutting against anannular shoulder 48. This bearing sleeve member 44 is formed of suitablebearing material to run against the cylinder wall 22, for example, it isformed of bearing bronze. It is retained by an end cap 50 of toughhardened steel secured to the weight 42 by detachable fastening meansshown as a plurality of machine screws 52.

In order to form a fluid seal near the end of the piston weight assembly24, a plurality of piston rings 54 are provided. These piston rings 54are mountedv in an annular gland member 56 which is retained by the endcap 50 together with the bearing sleeve 44. There is a the rings 54 withaccurate firm support, because the the floating gland 56 and thecylinder wall. Thus, the piston rings continue to be well supportedtolast a long time. The way in which the piston rings and gland areassembled is that the piston rings are split so as to be inserted intothe grooves in the annular gland; whereas the gland 56 itself has acontinuous circular configuration and is placed adjacent to the bearingsleeve 44 before the end cap 50 is secured in place. There is a closefit between the end cap 50 and the lower radial surface of the glandmember 56 and also a close fit between the bearing member 44 and theadjacent upper radial surface of the gland member. Thus, an effectivefluid seal is provided by the piston rings 54 and the gland 56 eventhough there is a large clearance space 58 beneath the gland.

In my presently preferred illustrative embodiment as shown, the cylinderbottom assembly 26 includes a second piston 60. This second piston 60 isadapted to move up and down for'a'limited travel distance within asecond cylinder 61 which is defined by a lower extension of the cylinderwall 22 below the level of the bounce chamber 34. To retain the piston60 within the cylinder 61, there is an annular stop shoulder 63surrounding the piston 60. An annular retainer and bearing element 65defines the lower end of the cylinder 61. The retainer and bearingelement 65 is secured by large machine screws 67 to a mounting ring 69which is welded to the exterior of the cylinder wall 22. At the lowerend of the piston 60, there is a coupling flange 71 adapted to begripped by the detachable coupling 30. The detachable coupling 30 isformed by two semicircular clamps with protruding mating flanges 73which are secured together by bolts 75.

As an alternative embodiment shown in FIG. 21, it is noted that thecylinder bottom assembly 26 can be defined by a closed lower end of thecylinder 22. In other words, in such an alternative embodiment, thesecond piston 60 is replaced by a fixed member 60A which is welded orotherwise attached to the lower portion of the cylinder wall 22, so asto be effectively integral with the cylinder wall 22.

It is my present preference to utilize a cylinder bottom assembly 26which includes a relatively movable second piston 60, because the use ofthis second piston 60 de-couples the cylinder wall 22 from the pile 28.this de-coupling of the cylinder wall 22 from the pile 28 reduces theamount of mass tobe driven downwardly when the powerful driving thrustis applied to drive the pile 28. i

As explained above, the fluid injection means 36 includes the drivingfluid chamber 38 and the control valve mechanism 40. It is the'purposeof this fluid injection means 36 to inject pressurized fluid through aninjection port 62 into the bounce chamber 34 beneath the descendingpiston weight assembly 24. The injection of the pressure fluid iscontrolled by the valve mechanism 40.

The driving fluid chamber means 38 is located within the second piston60 of the cylinder bottom assembly 26. The chamber bore 64 is lined by acylinder sleeve 66. A bottom flange 68 of an upstanding valve stem guide70 lines the bottom of the driving fluid chamber 38. The guide 70 has abore 72, and a valve stem 74 of valve member 76 extends into this bore72. The valve member 76 has a conical valve surface 78 which seatsupwardly against a conical valve seat 80 formed in the end cap 82 of thesecond piston 60. This second piston is provided with a bearing sleevemember 84, piston rings 86 and an annular gland 88 having annularclearance 58 similar to those elements for both ends of the pistonweight assembly 24.

In order to actuate the valve mechanism 40 by the piston weight 24,there is an upwardly extending actuator 91 integral with the valvemember 76. The actuator 91 is equipped with pressurized fluid trappingmeans 93 in the form of an enlarged cylindrical plunger. This plunger 93can be depressed to fit snugly into the port 62 to trap pressurizedfluid in the bounce chamber 34.

When the valve member 76 is depressed away from its valve seat 80,pressurized fluid in the driving fluid chamber 38 can rush up throughmultiple channels (FIG. 4) to bypass the perimeter of the valve member76 so as to be injected through the port 62 into the bounce chamber 34.The channels 90 are formed by grooves between lands 92 in the interiorof the cylinderical liner 66.

The pressurized fluid is supplied from a suitable source, for example,such as the pressure storage tank (not shown) of an air compressor (notshown). The compressed air is at a suitable pressure of, for example, 80pounds per square inch (p.s.i.) to 3,000 p.s.i.

When the valve member 76 is depressed, its annular groove 95 (FIG. 3)cooperates with the upper end of the valve guide 70 (as seen in FIG. 12)to act as resilient deceleration means by trapping fluid in the groove95. This trapped fluid provides resilient deceleration for the depressedvalve member to prevent its banging down on the guide 70.

The pressurized fluid is fed to, the pile driver system 20 through aflexible pressure hose line 94 and through a connection fitting 96. Thisfitting 96 feeds into an input passage 98 which'communicates with thebore 72 of the valve stem guide 70. The pressurized fluid from the bore72 flows through a constricted passageway 100 into the driving fluidchamber 38. When the valve stem 74 is in its uppermost position as shownin FIG. 3, the pressurized fluid can also flow through a less restrictedpassageway 1 or into the chamber 38. The two passageways 100 and 102 arein parallel flow relationship; the lower constricted one 100 is alwaysopen, but the upper unrestricted one 102 is shut off when the valvemember 76 together with its stem 74 is depressed by the piston weight24.

After the piston weight 24 has bounced upwardly from the cushion ofpressurized fluid, as shown in FIG. 13, the expanded pressure fluid 104is released from the cylinder 23 through a plurality of outlet ports 106in the cylinder wall 22. The outlet ports 106 communicate with anannular muffler chamber 108 defined by a removable muffler housing 109which includes a pair of spaced cylindrical walls 110 and 112. Themuffler housing walls 110 and 112 are rigidly interconnected by a bottomring plate 1 14 which is detachably secured to a mounting ring 116 by apluralityof bolts 118. The mounting ring I 16 is secured to the outsideof the cylinder wall 22 by welding. I

Shown in FIGS. 5 and 6 is the upper end of the re movable muffler 109.The annular muffler chamber 108 communicates through multiple ports 120with a quantity of oil air separating material 122 in the top of anannular muffler chamber 123 for separating droplets of lubricating oilfrom the expanded pressure fluid 104 after passing through the ports120. The material 122 is coarse stainless steel wool matting. Aremovable cover 124 secured by screws 126 enables the oil separatingmaterial 122 to be removed and replaced.

The expanded pressure fluid 104 flows down through the material 122,then down through the multiple holes 127 in a material support ring 129,and as shown in FIG. 6, the fluid 104 then flows into an inverted U-shaped fluid outlet baffle 128. The interior of the baffle 128communicates with an atmospheric vent 130 through which the expandedpressure fluid passes out into the atmosphere. The purpose of the baffle128 is to prevent the separated oil droplets from being blown out intothe atmosphere.

As shown in FIG. 6, the separated oil droplets 132 fall from theseparation material 122 in the chamber 123; and as shown in FIG, 3, thisoil collects in an annular reservoir 134 at the bottom of the chamber123. Thus, an oil reservoir is provided for the self-containedlubrication system which will be explained further below.

The muffler housing 109 can be removed to provide access to the ports106, if desired, by unscrewing the bolts 118 (FIGS. 3 and 7). As shownin FIG. 6, the top of the muffler housing 109 has an O-ring seal 136 forsealing the muffler chamber 108. Thus, the seal 136 can be slid up alongthe exterior of the cylinder wall 22 for removing the muffler housing109. With reference to FIG. 1, the mounting 138 for the lead guides andthe upper muffler and air filter 140 can be removed so as to permitcomplete removal of the muffler housing 109, if desired.

The self-contained lubrication system is shown in greatest detail inFIGS. 7 and 8. The level of the oil in the reservoir 134 can be seen byobserving an oil gauge 135 having a transparent non-breakable plastictube. Oil from the reservoir 134 can flow down through an oil supplypassage 142 into an inlet passage 144 sealed by a seal 145 andcommunicating with the inlet chamber 146 of an oil filter assembly 150.An annular filter cartridge 148 of filter material such as feltseparates the inlet chamber 146 from an outlet chamber 152 through whichpasses the end cap retainer bolt 154. The filter element 148 can beremoved and replaced by unscrewing the bolt 154 and removing the cap 156and its associated oil lines 158 and 159.

The filtered oil is fed from the outlet chamber 152 through a passage157 in the cap and through oil feed lines 158 and 159 leading to an oilpump 160. The line 158 feeds through a check valve 162 into alowpressure pump chamber 164 containing a pump piston 166. This piston166 pumps oil at low pressure through a check valve 168 and through anoil line 170 extending up to an oil hole 172' (FIG. 1) for dispensinglubricating oil above the piston weight assembly 24 to lubricate thepiston 24 and cylinder wall 22.

The other feed line 159 feeds through a check valve 174 into ahigh-pressure pump chamber 176 containing a smaller diameter piston 178.This piston 178 pumps oil under high pressure through a check valve 179into an oil line 180 extending down to a swivel 182 (FIG. 8) on theinlet connection fitting 96 for the pressurized fluid. The swivel 182has a passage 183 and an annular channel 184 for feeding oil inwardthrough a pair of oil holes into the bore 97 of the fitting 96.

Thus, the lubricating oil is mixed with the incoming pressurized fluid,and thereby oil is dispensed up through the passage 98 so as tolubricate the fluid injection means 36 including the valve mechanism 40.this 10 oil entering through the passage 98 also serves to lubricate thebounce chamber 34, the piston 60 and the cylinder wall 22 surroundingthe piston 60.

Inviting attention again to FIG. 7, it is noted that pistons 166 and 178are connected together to form a double piston. A spring 186 in thelow-pressure pump chamber 164 urges both pistons 166 and 178 toward theleft. In other words, the spring 186 urges the pistons 166 and 178 inthe direction of their intake stroke. The high pressures occuring in thebounce chamber 34 are utilized to drive the pistons 166 and 178 towardthe right, i.e. in the direction of their expulsion (pumping) stroke. asmall port 188 in the cylinder wall 22 communicates through drilledpassages 189 in a base plate 190 with a passage 192 leading into thepiston-actuating chamber 194. The base plate 190 serves to support boththe oil filter assembly and the oil pump 160. This base plate can bedetached from the outside of the cylinder wall 22. As shown in FIG. 3,this base plate is removably secured by machine screws 196 (only one canbe seen in FIG. 3).

When driving a pile, as shown in FIGS. 1 and 2, the pile driver systemis guided by a pair of spaced parallel vertical guide rails 200 and 201,which are called leads. The use of leads is well known in the art ofdriving piles, and their usage is not claimed as novel. These leads areengaged by lower and upper guides 204 and 206 which straddle therespective leads and are greased so as to slide easily down along theleads. The lower pair of guides 204 are attached by a mounting clampring 208 (FIG. 2) which surrounds the muffler housing 109. This lowermounting clamp ring 208 is formed in two semi-circles with protrudingmating flanges 209 secured together by bolts 210. Similarly, the upperpair of guides 206 are attached by a mounting clamp ring 138 surroundingthe cylinder wall 22. The upper clamp ring 138 is formed in twosemi-circles with protruding mating flanges 213 secured together bybolts 214.

In order to allow atmospheric air to flow in and out of the upperportion of cylinder 23 above the piston weight 24, there are provided aplurality of vent ports 216 (FIG. 15) communicating with an annularmuffler and air filter housing 140. This housing defines inner and outerannular muffler chambers 218 and 220. FIG. 15 shows the atmospheric air222 being expelled from the cylinder 23, because the piston weight 24 isrising.

It will be understood that as soon as the piston 24 begins descendingagain, the atmospheric air will be sucked back into the cylinder 23. Toexclude dust and dirt there is an air. filter element 224 in the chamber220 adjacent to the atmospheric vent 226.

In order to provide various driving modes for the pile driver system 20,various sizes of head plugs 230 (FIG. 15), 230A (FIG. 1 are utilized.The head plugs are removably secured in the top of the cylinder wall 22,by detachable fastening means 232 shown as machine screws. The deep headplug 230A shown in FIG. 1 extends down so far that it blocks the ventports 216, thus producing the double-acting driving mode, as will beexplained in detail further below.

The shallow head plug shown in FIG. 15 produces a single-acting drivingmode.

When the piston weight assembly 24 makes extreme upward excursionswithin the cylinder 23, as shown in FIG. 16, then the single-actingdriving mode automatically converts to a double-acting mode.

In use, the pile driver system 20 (FIG. 1) or 20A (FIG. 20) or 208 (FIG.21) can be supported by a cable 236 (FIG. 1) from a suitable crane (notshown) attached to suitable support means (234), such as connectionmeans attached to the upper end of the pile driver, for example, to thehead plug 230 or 230A.

When used in the pile-extraction mode, as shown in FIGS. 17 and 18, thesupport cable 236 can advantageously be fastened to connection means 238attached to a pressure-fluid cylinder 240 having a piston 242 thereinwith a chamber 244 below the piston. The'piston rod serves as supportmeans 234 attached to the upper end of the pile driver. Pressurizedfluid, for example, such as compressed air or other gas under pressure,is supplied from a pressurized fluid source 246, such as the receiver ofan air compressor. This pressurized fluid is supplied through anadjustable pressure regulator 248 into the cylinder chamber 244.

The regulator 248 is adjusted by the operator such 1 that the totalforce developed by the pressurized fluid in the chamber 244 actingupwardly upon the working area of the piston 242 is moderately less thanthe safe maximum lifting load of the crane pulling on the cable 236.

It will be understood that when acting in the pileextraction mode (asshown in FIGS. 17 and 18) a large upward pull is being exerted by thecable 236, and the pile driver is arranged to deliver jarring upwardblows so as to extract the pile 28. Thus, by regulating (248) thepressure, the fluid cylinder and piston 240, 242, 244 serve as overloadprotection means for the crane (or other lifting means being used).Also, this fluid cylinder and piston serve as mechanical shock absorbermeans, because the fluid (air or gas) in the chamber 244 is compressibleand serve as a resilient support. In this way the cable 236 and crane orother lifting means are spared from experiencing the wear and tear whichwould otherwise result from the jarring action of the pile driver. I

In the pile extraction mode, the reciprocating piston weight 24 travelsup, as shown in FIG. 16, near to the head plug 230, such that thetrapped compressed air (shown by double-headed arrows) in the upper endof the cylinder 23 beneath the head plug 230 exerts an upward thrust onthe pile driver during each stroke of the piston weight 24. If desired,the upper end cap 50 of the reciprocating piston weight 24 can bearranged to strike up against the head plug 230 to exert an upwardimpact for jarring the pile loose. This upward striking is accomplishedby installing a head plug which extends down to the level of the ventports 216.

The upward pull of cable 236 (FIG. 17) on the pile driver causes theannular shoulder 63 (FIG. 18) of the second piston 60 to engagetheretainer stop and bearing element 65. There is a loose coupling 250which is connected by the coupling 30 to the cylinder bottom assembly60. This loose (or overriding) coupling 250 permits downward motion ofthe cylinder bottom assembly 60 without imposing any downward thrust onthe pile 28. However, the upward thrust occurring at the peak of eachupward stroke of the piston weight 24 is transmitted by the coupling 250to the pile '28 being extracted.

As an example, the pile 28 (FIGS. 17 and 18) is shown as an H-beam pile,but other types of piles can also be extracted with advantage by use ofthe invention.

The loose coupling 250 is shown as including a cylinder having anabutment 254 at its lower end. An extractor rod 256 is attached to thepile 28 being extracted. A head 252 on this rod strikes against theabutment 254for delivering upward thrusts to the pile for extracting it.

FIG. 19 shows the pile driver system 20 (FIG. 1) or 20A (FIG. 20) or 203(FIG. 21) being used for driving a timber pile 28. A conical guide 258is shown for centering the pile driver 20, or 20A, or 203 upon thetimber pile 28. The guide 258 is secured by a clamp to an With referenceto FIG. 20, a modified pile driver sys- I tem 20A is shown embodying theinvention and adapted for practicing the method of the invention.

The only change from 'the pile driver system and method 20, as describedabove, is that the valve actuator 91A does not include fluid-trappingmeans in the form of an enlarged head such as shown at 93 (FIG. 3).

Thus, in FIG. 20, when the piston weight assembly 24 descends, it isdecelerated by the pressure fluid in the bounce chamber and thereafterforces this fluid back down into the driving fluid storage chamber 38.Impact at reduced velocity is thereby allowed to occur between thepiston weight 24 and the second piston 60. Thereafter, the piston weight24 is re-accelerated upwardly by pressure fluid released by open valve40 from the driving fluid chamber 38.

Accordingly, it will be understood that FIG. 20 is well adapted toprovide the fourth mode set forth in the introduction, namely,pre-stress plus impact plus thrust. The pre-stressing occurs while thecushion of pressure fluid injected into the bounce chamber by the valvemeans 40 plus any residual fluid in the bounce chamber is deceleratingthe piston weight. This pre-stressing removes all of the play betweenthe second piston 60 and the pile 28. Then, when the piston weight 24strikes the second piston 60 with an impact, as shown in FIG. 20, theresulting blow starts the pile moving downwardly, as indicated by thetwin arrows near the coupling 30 in FIG. 20. Following impact, there isa powerful thrust delivered to the moving pile to keep it moving down ina highly effective driving mode. This powerful enduring thrust isdelivered to the pile during the reacceleration of the piston weightupwardly.

There is an advantageous method for increasing or decreasing the amountof impact occurring in the system 20A of FIG. 20. The actuator 91A islengthened to decrease the amount of impact and is shortened to increasethe amountof impact. This lengthening or shortening is accomplished byremoving the valve member 76 and replacing it with one having a longeror shorter actuator 91A, as desired.

When a longer actuator 91A is employed, the valve 40 is opened to injectthe pressurized fluid beneath the descending position weight 24 when itis farther from the cylinder bottom assembly 60. The pressurized fluidthereby has a longer time to act and thus decelerates the piston weight24 to a slower velocity before impact occurs, producing a reducedimpact, and vice versa.

If a sufficiently long actuator 91A is employed, then impact will notoccur, provided that the fluid driving chamber 38 is sufficiently largeto adequately fill the bounce chamber with pressurized fluid at asufficient 13 pressure to completely decelerate the piston weight in thetime available.

This pre-stress plus impact plus thrust driving mode can be used toadvantage for driving very stubborn piles. The amount of impact can beadjusted, in the manner explained above, so as to start the pile moving.Then the pile driver provides a powerful, enduring thrust to push themoving pile on down further in an effective efficient operation. Theamount of impact can be just sufficient to start the pile moving, beingvery effective because the pile is already pre-stressed. Thus, excessiveimpact as occurs in the prior art is avoided. The powerful, enduringafter thrust is very effective because it is delivered to an alreadymoving pile.

With reference to FIG. 21, another modified pile driver system B isshown embodying the invention and adapted for practicing the method ofthe invention. The only change from the pile driver system and method20, is that the cylinder bottom assembly 60A in the system 208 issecured to the lower end of the'cylinder wall 22. This cylinder bottomassembly is attached by a large number of strong machine screws 262.This attachment is an advantage because it reduces the number of movingparts in the pile driver system to two, namely, the piston weightassembly 24 and the valve member 76. (In counting the moving parts astwo, the lubrication system 150, 160 is not being counted, because thelubrication system is shown as an advantageous feature of theembodiments shown. However, other conventional lubrication systemscould. be employed.)

It is my present preference to use the pile driver system 20 or 20Awhich has three moving parts 24, 60 and 76, because the movement of thecylinder bottom 60 reduces the effective mass to be driven byde-coupling the mass of the cylinder wall 22 (together with everythingrigidly attached to the wall 22) from the pile being driven, thus makingthe driving job correspondingly easier. However, in certain pile drivingapplications, the advantage of fewer moving parts may outweigh theadvantage of reduction of the effective mass being driven.

Further Aspects of Operation A number of the operational features andadvantages of this invention are explained above in connection with thedescription of the method and systems shown. Further aspects of theoperation are set forth in this part of the specification.

When the pile driving systems 20, 20A or 20B are set up ready to drive apile, the reciprocating up-and-down motion of the massive piston weight24 is started as follows: Initially the piston weight 24 is resting downstationary upon the cylinder bottom assembly 60 or 60A, as the case maybe. Thus, the valve actuator 91 or91A is depressed so that the valvemember 76 is spaced from its seat. There is a modest clearance aroundthe enlarged head 93 so that fluid can leak from the pressure fluiddriving chamber 38 into the bounce chamber sure fluid storage chamber 38is now supplied with '14 pressurized fluid through the constrictedpassage 100 (FIG. 3). (Large passage 102 is now blocked by thestationary depressed stem 74.)

In the system 20 or 20B, the pressurized fluid enters the bounce chamberby leaking through the clearance around the plunger head 93. The pistonweight 24 is raised up by the entering fluid, and the pressure fluid inthe bore 72 acts on the stem 74 to cause the valve member 76 to move uptogether with the piston weight 24. When the head 93 leaves the injectorport 62', the accumulated pressure fluid in the chamber 38 rushes upinto the bounce chamber 34 to suddenly push the piston weight up. Thevalve member 76 rises up against its seat to close the valve 40. Thepassage 102 is unblocked because the stem 74 has moved up. Thus, thepressure fluid now rushes through both passages and 102, so that thepressure in chamber 38 is raised up substantially to the supplypressure.

In the pile driver system 20A of FIG. 20, the operator starts the pistonweight 24 in the same way as for systems 20 and 20B, namely, by suddenlystarting the flow of pressure fluid through the line 94. The passage 100allows pressure fluid to surge into the storage chamber 38, and it flowsup through the open valve 40. This surge of pressure fluidup through theopen valve 40 suddenly pushes the piston weight 24 upwardly.

The sudden upward push on the piston weight 24(in system 20, 20A or 20B)causes it to rise up, as shown in FIG. 13, to the point where the outletports 106 are unblocked. The expanded pressure fluid in the bouncechamber 34 is released through ports 106, allowing the 7 is greater thanthe first one, because the pressure in storage chamber 38 has becomemore nearly equal to supply pressure. Thus, the piston weight 24 isaccelerated more and rises up, as shown in FIG. 13, further be yond theports 106.

The expanded fluid is again released and the piston weight falls downagain, as shown in FIG. 9. It is descending faster than the first time,and it opens the valve, as shown in FIG.'10, this time the valve beingopened wider and longer. than the first time, because the piston weightdescends farther. Accordingly, even more pressure fluid is injected tohurl the piston weight up farther than the second time, and so forth.

After about three to six cycles, the piston weight 24 reaches its fullamplitude for driving the pile. As shown in FIGS. 9, 10, ll, l2, l3 and14, when the piston weight has reached its full amplitude, in each cycleit descends so far that the plunger head 93 is driven down to block theport 62, as shown in FIG. 11.

The following is an explanation of a typical operating cycle: FIG. 9shows the piston weight 24 descending. It is below the level of theoutlet ports 106, and so any residual pressure fluid in the bouncechamber 34 is being compressed. This compression begins to deceleratethe piston weight, and the compression also begins to exert a downwardthrust on the cylinder bottom assembly 26, thereby beginning to thrustdown upon the pile 28. In this way, the bottom assembly 26, coupling 32,and pile 28 are prestressed to remove all play therein.

FIG. 3 shows the piston weight assembly at the moment it comes incontact with the head 93 of the actuator 91.

FIG; 10 shows the valve fully opened by depression of the actuator. Thepressure fluid is being injected through the port 62 into the bouncechamber. The resultant sudden increase in pressure beneath the pistonweight 24 increases its decelerationand produces a powerful down thruston the pile 28, as indicated in FIG. 10 by the twin arrows on theadapter 32.

FIG. 11 shows the injected port 62 closed by the fluid trapping headmeans 93. The injection pressure fluid and any residual pressure fluidremaining in the bounce chamber from the previous cycle are now trappedby blockage of the port 62. Accordingly, the descending piston weightproduces a tremendous compression of the trapped fluid, as indicated bythe compression arrows C (FIG. 11) and still greater compression C (FIG.12).

The increasing compression pressures (C and C) produce a tremendous andenduring downward thrust on the pile, as shown by the twin arrows inFIGS. 11 and 12 near the coupling 30. A resilient compressed fluidcushioned bouncing action occurs, i.e. the piston weight is completelydecelerated and is re-accelerated upwardly, as shown in FIG. 13.

The re-acceleration upwardly, such as occurs between FIGS. 12 and 13,produces a continuing powerful downward thrust on the-pile until theports 106 are uncovered.

Thus, there-is a downward thrust occurring during the operation shown inFIGS. 9, 3, 10, 11 and 12 and during the re-acceleration occurringbetween the positions shown in FIGS. 12 and 13.

When a deep head plug 230A is being used, as shown in FIG. 14, thenatmospheric air is trapped above the piston weight 24, so as to producea double-acting piston effect. The downward push of the trapped air onthepiston, which has risen up near the head plug 230A, is indicated in FIG. 14 by the plural arrows beneath the head plug.

It is noted that a two-stage trapping action of compressible'fluidoccurs beneath the descending piston in the systems and 20B. In FIG. 9pressure fluid is trapped beneath the descending piston because ports106 and valve 40 areclosed. After the driving pressure fluid has beeninjected (FIG. 10), a second trapping ac tion occurs as indicated at Cand C in FIGS. 11 and 12 because the injector port 62 is closed.

It is noted that in the pile extraction, the piston weight 24 is startedto reciprocate by first slacking the cable 236 (FIG. 17), so that thepile driver 20 is resting down upon the pile, then the flow of pressurefluid is turned on in the line 94 to start the piston weight up anddown. As soon as it is reciprocating at full amplitude, the upward pullis applied to cable 236 to begin extraction.

In all of the systems shown, the reciprocation of the piston weight 24is stopped by shutting off the flow of pressure fluid through the hoseline 94.

The pile driver system 20A or 208 can also be used for pile extractionin the same general mariner as the pile driver system 20.

Advantageously, the operator can increase the time duration of eachfluid-cushioned powerful driving thrust and decrease the peak forceoccurring during each driving thrust by increasing the extent oftrapping of pressurized fluid by the trapping means 93 (FIG. 3), andvice versa. By increasing the height of trapping means 93, port 62becomes blocked when piston 24 is at a larger predetermined distancefrom the bottom assembly 26, thus increasing the extent of trapping, andvice versa. For convenience, if desired, detachable inter-changeableheads 93 can be provided which are attached by screw means to theactuator 91.

I claim:

1. Pile driver apparatus for driving a pile into the earth comprising acylinder wall defining a cylinder, a massive piston weight movable upand down within said cylinder, a bottom assembly associated with saidcylinder wall and positioned below said piston weight adapted to becoupled in thrust transmitting relationship to the pile to be driven,said piston weight and cylinder bottom assembly defining a bouncechamber between them, compressible pressurized fluid storage chambermeans adapted to communicate with said bounce chamber, a valve forblocking communication between said storage chamber and said bouncechamber, input means for feeding pressurized fluid into said storagechamber from a remote source of supply, and means for opening said valvefor injecting pressurized fluid from said storage chamber into saidbounce chamcylinder.

2. Pile driver apparatus for driving a pile into the earth, as claimedin claim 1, in which said cylinder bottom assembly includes saidcompressible pressurized fluid storage chamber means. 3. Pile driverapparatus for driving a'pile into the earth, as claimed in claim 1, inwhich said means for opening said 'valve is actuated by the descendingpiston weight.

4. Pile driver apparatus for driving a pile into the earth, as claimedin claim 1, including trapping means for trapping pressurized fluid inthe bounce chamber beneath the descending piston weight for producingpressurized fluid cushioned bouncing action of the piston weightproviding a powerful downward thrust upon said cylinder bottom assemblyupon each bounce of the piston weight to be transmitted to the pile fordriving it into the earth.

5. Pile driver apparatus for driving a pile into the earth, as claimedin claim 1, in which said cylinder bottom assembly includes a secondpiston movable up and down with respect to the cylinder wall and adaptedto be coupled to the pile in thrust transmitting relationship.

6. Pile driver apparatus for driving a pile into the earth as claimed inclaim 1, in which said cylinder bottom assembly includes an annularflange at the lower end thereof, and a clamp ring for encircling saidannular flange for coupling the cylinder bottom assembly to the pile inthrust transmitting relationship.

7. Pile driver apparatus for driving a pile into the earth as claimedin'claim 1, in which an outlet port is provided in the cylinder wall forreleasing expanded pressurized fluid from the bounce chamber, and amuffler enclosing the outlet port.

8. Pile driver apparatus for driving a pile into the earth as claimed inclaim .7, in which said muffler includes means for separatinglubricating oil from the pressurized fluid.

9. Pile driver apparatus for driving a pile into the earth as claimed inclaim 8, in which a lubricating oil l7 reservoir is associated with saidmuffler, and a selfcontained lubrication system associated with said oilreservoir, said lubrication system being actuated by the pressurechanges in said bounce chamber.

10. Pile driving apparatus comprising a piston weight of large massadapted to reciprocate up and down within a cylinder, said cylinderhaving a second piston adapted to reciprocate up and down within thelower end of the cylinder and adapted to be coupled in thrusttransmitting relationship to the pile being driven, said piston weightand second piston defining a bounce chamber between them, said secondpiston having a pressure fluid inlet passage, a pressure fluid storagechamber in said second piston supplied by said passage, and a valveadapted to be opened to release the pressure fluid from the storagechamber into the bounce chamber when the piston weight descends andapproaches the second piston.

l1. Pile driving apparatus as claimed in claim 10, in which trappingmeans are provided for trapping the pressure fluid in the bounce chamberafter the pressure fluid has been released from the storage chamber intothe bounce chamber.

l2. Pile driving apparatus as claimed in claim 11, in which saidtrapping means are included in the valve for blocking off communicationbetween the bounce chamber and the storage chamber.

13. Pile driving apparatus as claimed in claim 10, in which said valveincludes an actuator extending upwardly adapted to be engaged by thedescending piston weight for opening said valve to release the pressurfluid.

14. Pile driving apparatus as claimed in claim 13, in which said secondpiston has a port surrounding said actuator for providing. communicationbetween the storage chamber and the bounce chamber when the valve isopened, and an enlarged head on said actuator adapted to be depressedinto said port for blocking said port for trapping the pressure fluid insaid bounce chamber beneath the descending piston weight.

15. Pile driving apparatus as claimed in claim 13, in which said valveincludes a valve member which is depressed by said actuator, saidstorage chamber and valve member having interfitting parts providing acushion of pressure fluid preventing the valve member from strikingbottom when it has been depressed.

l6. Pile driver apparatus comprising a cylinder wall defining acylinder, a massive piston weight movable up and down within saidcylinder, a bottom assembly associated with said cylinder wall andpositioned below said piston weight, said piston weight and cylinderbottom assembly defining a bounce chamber between them, said cylinderbottom assembly including means defining a storage chamber for storageof pressurized fluid, said storage chamber having a port communicating18' with said bounce chamber, said storage chamber having a valve guidewith a vertical bore, a valve member having a stem extending down intosaid bore, said valve .rnember being movable up and down and when in itsupper position said valve member blocking said port, said cylinderbottom assembly having an input passage for pressurized fluidcommunicating with the bore of said valve guide and said valve guidehaving an opening providing communication between said bore and saidstorage chamber, and said valve member being moved down by thedescending piston weight for opening said port to inject pressurizedfluid into said bounce chamber.

17. Pile driver apparatus as claimed in claim 16, in which said valveguide has an upper and lower opening each providing communicationbetween the bore and the storage chamber, the upper opening being largerthan the lower one, and said valve stem blocking the upper opening whenthe valve member is moved down.

18. Pile driver apparatus comprising a cylinder wall defining acylinder, a massive piston weight movable up and down within saidcylinder, a bottom assembly associated with said cylinder wall andpositioned below said piston weight, said piston weight and cylinderbottom assembly defining a bounce chamber below said piston weight andabove said bottom assembly, said cylinder bottom assembly includingmeans defining a storage chamber for storage of pressurized fluid withinsaid bottom assembly, said storage chamber having a port communicatingbetween the top of said storage chamber and said bounce chamber, a valvemember associated with said port, said valve member being movable up anddown and when in its upper position said valve member blocking saidport, said cylinder bottom assembly having an input passage for feedingcompressible pressurized fluid intosaid storage chamber, actuatormeansextending into said bounce chamber for moving said valve member downwhen the piston weight is descending for opening said port to injectcompressible pressurized fluid from said storage cham-- ber up into saidbounce chamber beneath the descending piston weight to bounce the pistonweight upwardly, and said cylinder wall having outlet port means forreleasing the expanded compressible pressurized fluid from the cylinderafter the piston weight has bounced upwardly to repeat the cycle,whereby the piston weight quietly bounces up and down within saidcylinder. I

19. Pile driver apparatus as claimed in claim 18, in which means areprovided for blocking said port after compressible pressurized fluid hasbeen injected into the bounce chamber for trapping the compressiblepressurized fluid beneath the descending piston weight.

1. Pile driver apparatus for driving a pile into the earth comprising acylinder wall defining a cylinder, a massive piston weight movable upand down within said cylinder, a bottom assembly associated with saidcylinder wall and positioned below said piston weight adapted to becoupled in thrust transmitting relationship to the pile to be driven,said piston weight and cylinder bottom assembly defining a bouncechamber between them, compressible pressurized fluid storage chambermeans adapted to communicate with said bounce chamber, a valve forblocking communication between said storage chamber and said bouncechamber, input means for feeding pressurized fluid into said storagechamber from a remote source of supply, and means for opening said valvefor injecting pressurized fluid from said storage chamber into saidbounce chaMber when the piston weight is descending withing thecylinder.
 2. Pile driver apparatus for driving a pile into the earth, asclaimed in claim 1, in which said cylinder bottom assembly includes saidcompressible pressurized fluid storage chamber means.
 3. Pile driverapparatus for driving a pile into the earth, as claimed in claim 1, inwhich said means for opening said valve is actuated by the descendingpiston weight.
 4. Pile driver apparatus for driving a pile into theearth, as claimed in claim 1, including trapping means for trappingpressurized fluid in the bounce chamber beneath the descending pistonweight for producing pressurized fluid cushioned bouncing action of thepiston weight providing a powerful downward thrust upon said cylinderbottom assembly upon each bounce of the piston weight to be transmittedto the pile for driving it into the earth.
 5. Pile driver apparatus fordriving a pile into the earth, as claimed in claim 1, in which saidcylinder bottom assembly includes a second piston movable up and downwith respect to the cylinder wall and adapted to be coupled to the pilein thrust transmitting relationship.
 6. Pile driver apparatus fordriving a pile into the earth as claimed in claim 1, in which saidcylinder bottom assembly includes an annular flange at the lower endthereof, and a clamp ring for encircling said annular flange forcoupling the cylinder bottom assembly to the pile in thrust transmittingrelationship.
 7. Pile driver apparatus for driving a pile into the earthas claimed in claim 1, in which an outlet port is provided in thecylinder wall for releasing expanded pressurized fluid from the bouncechamber, and a muffler enclosing the outlet port.
 8. Pile driverapparatus for driving a pile into the earth as claimed in claim 7, inwhich said muffler includes means for separating lubricating oil fromthe pressurized fluid.
 9. Pile driver apparatus for driving a pile intothe earth as claimed in claim 8, in which a lubricating oil reservoir isassociated with said muffler, and a self-contained lubrication systemassociated with said oil reservoir, said lubrication system beingactuated by the pressure changes in said bounce chamber.
 10. Piledriving apparatus comprising a piston weight of large mass adapted toreciprocate up and down within a cylinder, said cylinder having a secondpiston adapted to reciprocate up and down within the lower end of thecylinder and adapted to be coupled in thrust transmitting relationshipto the pile being driven, said piston weight and second piston defininga bounce chamber between them, said second piston having a pressurefluid inlet passage, a pressure fluid storage chamber in said secondpiston supplied by said passage, and a valve adapted to be opened torelease the pressure fluid from the storage chamber into the bouncechamber when the piston weight descends and approaches the secondpiston.
 11. Pile driving apparatus as claimed in claim 10, in whichtrapping means are provided for trapping the pressure fluid in thebounce chamber after the pressure fluid has been released from thestorage chamber into the bounce chamber.
 12. Pile driving apparatus asclaimed in claim 11, in which said trapping means are included in thevalve for blocking off communication between the bounce chamber and thestorage chamber.
 13. Pile driving apparatus as claimed in claim 10, inwhich said valve includes an actuator extending upwardly adapted to beengaged by the descending piston weight for opening said valve torelease the pressure fluid.
 14. Pile driving apparatus as claimed inclaim 13, in which said second piston has a port surrounding saidactuator for providing communication between the storage chamber and thebounce chamber when the valve is opened, and an enlarged head on saidactuator adapted to be depressed into said port for blocking said portfor trapping the pressure fluid in said bounce chamber beneath thedescending piston weight.
 15. Pile driving aPparatus as claimed in claim13, in which said valve includes a valve member which is depressed bysaid actuator, said storage chamber and valve member having interfittingparts providing a cushion of pressure fluid preventing the valve memberfrom striking bottom when it has been depressed.
 16. Pile driverapparatus comprising a cylinder wall defining a cylinder, a massivepiston weight movable up and down within said cylinder, a bottomassembly associated with said cylinder wall and positioned below saidpiston weight, said piston weight and cylinder bottom assembly defininga bounce chamber between them, said cylinder bottom assembly includingmeans defining a storage chamber for storage of pressurized fluid, saidstorage chamber having a port communicating with said bounce chamber,said storage chamber having a valve guide with a vertical bore, a valvemember having a stem extending down into said bore, said valve memberbeing movable up and down and when in its upper position said valvemember blocking said port, said cylinder bottom assembly having an inputpassage for pressurized fluid communicating with the bore of said valveguide and said valve guide having an opening providing communicationbetween said bore and said storage chamber, and said valve member beingmoved down by the descending piston weight for opening said port toinject pressurized fluid into said bounce chamber.
 17. Pile driverapparatus as claimed in claim 16, in which said valve guide has an upperand lower opening each providing communication between the bore and thestorage chamber, the upper opening being larger than the lower one, andsaid valve stem blocking the upper opening when the valve member ismoved down.
 18. Pile driver apparatus comprising a cylinder walldefining a cylinder, a massive piston weight movable up and down withinsaid cylinder, a bottom assembly associated with said cylinder wall andpositioned below said piston weight, said piston weight and cylinderbottom assembly defining a bounce chamber below said piston weight andabove said bottom assembly, said cylinder bottom assembly includingmeans defining a storage chamber for storage of pressurized fluid withinsaid bottom assembly, said storage chamber having a port communicatingbetween the top of said storage chamber and said bounce chamber, a valvemember associated with said port, said valve member being movable up anddown and when in its upper position said valve member blocking saidport, said cylinder bottom assembly having an input passage for feedingcompressible pressurized fluid into said storage chamber, actuator meansextending into said bounce chamber for moving said valve member downwhen the piston weight is descending for opening said port to injectcompressible pressurized fluid from said storage chamber up into saidbounce chamber beneath the descending piston weight to bounce the pistonweight upwardly, and said cylinder wall having outlet port means forreleasing the expanded compressible pressurized fluid from the cylinderafter the piston weight has bounced upwardly to repeat the cycle,whereby the piston weight quietly bounces up and down within saidcylinder.
 19. Pile driver apparatus as claimed in claim 18, in whichmeans are provided for blocking said port after compressible pressurizedfluid has been injected into the bounce chamber for trapping thecompressible pressurized fluid beneath the descending piston weight.